Avoid copying and strlen(3) in the FindClass path.

Change-Id: I789f3c883596d1852a2c1954ce7a207e6f937117
diff --git a/src/dalvik_system_VMRuntime.cc b/src/dalvik_system_VMRuntime.cc
index f8be881..de5252d 100644
--- a/src/dalvik_system_VMRuntime.cc
+++ b/src/dalvik_system_VMRuntime.cc
@@ -67,7 +67,7 @@
   std::string descriptor;
   descriptor += "[";
   descriptor += ClassHelper(element_class).GetDescriptor();
-  Class* array_class = class_linker->FindClass(descriptor, NULL);
+  Class* array_class = class_linker->FindClass(descriptor.c_str(), NULL);
   Array* result = Array::Alloc(array_class, length);
   if (result == NULL) {
     return NULL;